3D hexapod-shaped Co-ZIFs-S derived co nanoparticles embedded into nitrogen and sulfur co-doped carbon decorated with ruthenium nanoparticles as efficient catalyst for rechargeable lithium oxygen battery

Rechargeable lithium oxygen batteries (LOBs) are one of the most promising energy storage systems by virtue of their high energy density and environmental amiability. However, the development of LOBs is still hindered by some critical issues. Herein, 3D hexapod-shaped Co-ZIFs-thiourea/dimethyl sulfoxide (H-Co-ZIFs-S) derived Co nanoparticles embedded into nitrogen and sulfur co-doped carbon (H-Co-NSC) are developed, and then low content of ruthenium nanoparticles are decorated on the surface to obtain Ru/H-Co-NSC as efficient catalyst for LOBs. The Ru/H-Co-NSC catalysts exhibits unique structure and catalytic properties, such as accommodating the insoluble discharge product Li2O2, promoting the transportation of ions/O2, enhancing the electronic conduction, demonstrating excellent OER/ORR kinetics as well. In addition, the Ru-decorated nanoparticles could effectively suppress some side-reactions caused by the exposed carbon of H-Co-NSC in LOBs. First-principles Density functional theory (DFT) calculations reveal the cooperative effect of multiple active sites in Ru/H-Co-NSC can effectively promote the ORR/OER kinetics in LOBs. Therefore, the LOBs with Ru/H-Co-NSC cathode provide a positive catalytic capacity with low overpotential, large specific capacities, long cycle life and superior reversibility. Our work may pave the way to design more advanced catalysts for metal-air batteries with superior electrochemical performance.